Introduction
DirectoryWatcher watches a chosen directory and its subdirectory for changes. When a change is detected it sets its Icon in the system tray to 
, plays a sound, logs the change, and sets its state to �dirty�. If a file or directory is deleted, it logs the change, sets the state to be not �dirty� and sets the icon in the system Tray to 
. If a change is detected and the state is already dirty, no sound is played.
When you use the right mouse button on the tray icon, a context menu is displayed. By choosing �Properties� or double-clicking the tray icon, you go to the main window, where you see the log, make your settings, and reset the �dirty�-state.
The log shows the result of copying the file 02_step01_int.jpg in and deleting the file yoda.bmp. As you see, three change events are logged for a single file that gets moved/copied in. This is because the current version doesn�t filter and aggregate the events, which come from the underlying Framework-class FileSystemWatcher, which reports changes in a directory. More about the generated and used events can be found in the Technical section. The tool does its work to report changes in a chosen directory, while generating very little load on the system. It is written with the Visual Studio 2005 Beta 2 using Visual Basic .NET. You need the .NET Framework 2.0 to run this application.
Technical
In this sample, you see the use of a lot of Framework-classes and usage of the new and handy My Namespace.
Subscribing for the wanted events of the FileSystemWatcher:
HotSpotFileSystemWatcher.NotifyFilter = _
(NotifyFilters.LastAccess Or NotifyFilters.LastWrite Or _
NotifyFilters.FileName Or NotifyFilters.DirectoryName Or _
NotifyFilters.Attributes)
The WatcherChangeTypes.Created and WatcherChangeTypes.All in the changed event of the FileSystemWatcher are never fired. This is bad since I subscribed to the Attribute change, to reset the dirty flag, when a file gets read. But changes to the file attributes as lastaccesstime doesn�t fire an event in the FileSystemWatcher class. The creation and renaming of a folder are not distinguishable, both generate a rename, followed by a change event on the new folder. When a file gets copied in the watched folder, usually three change events on the file are logged, followed by one change event for its directory (none if it�s the root folder).
The generation of new empty files only issues a change event on the containing folder. Saving a small text causes two change events on the file and one on the containing folder. The delete of a file fires immediately a single delete event, but it is followed by a delayed change event on the containing folder, for example, when you select the containing folder in the Explorer. A rename of a file issues a rename event on the file followed by a change event on it. This in this application is no problem, since both a rename and change cause the �dirty�-state. But under other circumstances a timer must be used to distinguish between a change and rename event.
You can choose to search at the beginning for changes after the last program termination. The creation-time is only updated when the file is copied in, but not when it�s moved. Currently I check for the file and directory creation date and also the directory write date. This unfortunately fires a directory write, when a files get deleted, a condition on which we want to clear the �dirty state�.
For hiding the main-window at start up a workaround was needed, because Visible=False has no effect in the Load event from the form and in the designer the Visible setting is missing.
Have fun!
